The present invention generally relates to an exhaust backpressure tester, and more particularly, to such a tester which can be employed with a vehicle having an onboard pressure feedback electronic EGR system.
Exhaust systems in vehicles sometimes develop exhaust restrictions which prevent exhaust gases from flowing normally from their engines to the atmosphere. Such restrictions may result from excess carbon deposits in one portion of the exhaust system or from a damaged muffler. Exhaust restrictions create sluggish operation of the engine and, if left uncorrected, may result in damage to the engine.
A further problem which may occur in an exhaust system of a vehicle results when the system's catalytic converter becomes non-operational. While a non-operational catalytic converter would not normally result in a restriction in the exhaust system, it would result in pollutants, such as carbon monoxide, NOx, and hydrocarbons, entering the atmosphere in unreduced quantities.
In the past, technicians have attempted to accurately determine if an exhaust restriction was present in the exhaust system of a vehicle or if the catalytic converter was restricted or otherwise non-operational. This was done by tapping into the exhaust system, taking pressure readings of the backpressure of the system, and estimating whether the backpressure was acceptable. However, since technicians would make estimates without access to definitive acceptable and unacceptable backpressure values for the particular vehicle being tested, incorrect determinations were often made. Consequently, a number of exhaust system components, e.g., catalytic converters, which were not in need of repair were replaced, and components which were in need of repair were not repaired or replaced. Thus, the prior art technique for determining if an exhaust restriction exists in the exhaust system of a vehicle or if the catalytic converter is restricted or otherwise non-operational has been found to be highly unreliable.
Accordingly, a need exists for a reliable backpressure tester which can detect if an exhaust restriction exists in the exhaust system of a vehicle or if the catalytic converter in the vehicle is restricted or otherwise non-operational.